Broad band low frequency passive muffler

• US 5,350,888 A
• Filed: 12/16/1993
• Issued: 09/27/1994
• Est. Priority Date: 05/01/1992
• Status: Expired due to Fees

• Current Assignee: Tenneco Automotive Operating Company Incorporated (Apollo Global Management, Inc.)
• Original Assignee: Tennessee Gas Pipeline Company (El Paso Corporation)
• Inventors: Kraai, Leon A., Sager, Robert L. Jr.
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): LEE, EDDIE C H
• Application Number:
  US08/168,574
• Time in Patent Office: 285 Days
• Field of Search: 181/247, 181/252, 181/256, 181/267
• US Class Current: 181/247
• CPC Class Codes: F01N 1/006 comprising at least one perforated tube extending from inlet to outlet of the silencer
• CPC Class Codes: F01N 1/02 by using resonance
• CPC Class Codes: F01N 1/023 Helmholtz resonators
• CPC Class Codes: F01N 1/24 by using sound-absorbing materials F01N1/04, F01N1/06, F01N1/10, F01N1/14, F01N1/16 take precedence
• CPC Class Codes: F01N 2490/15 Plurality of resonance or dead chambers
• CPC Class Codes: F01N 2490/155 being disposed one after the other in flow direction

Abstract

A sound absorbing muffler used to attenuate noise carried by the exhaust gases of an internal combustion engine includes a straight-through flow tube of cross-section having no baffles or flow reversals. The muffler utilizes both reactive and dissipative components and includes an outer annular resonating chamber and an inner sound absorbing chamber. The muffler'"'"'s configuration produces effective broad band noise attenuation even at lower frequencies, yet low backpressure.

Claims

1. An acoustic muffler for attenuating sound waves, comprising:

an elongated, continuous, straight through tubular member;

an annular sound absorbing chamber surrounding said tubular member, said sound absorbing chamber containing sound absorbing material;

an annular resonating chamber surrounding said sound absorbing chamber, said sound absorbing chamber and said resonating chamber being of substantially equal length and defining a first and second end, said tubular member transversing said length of said chambers;

a first and second imperforate annular end chamber, each surrounding said tubular member and each being disposed adjacent to one of said first and second ends of said sound absorbing and resonating chambers respectively, said tubular member extending continuously from a first outer end of said first end chamber to a second outer end of said second end chamber;

a plurality of apertures formed on said tubular member allowing fluid communication between the volume within said tubular member and said sound absorbing chamber; and

a plurality of apertures allowing fluid communication between said sound absorbing chamber and said resonating chamber.

2. The muffler as set forth in claim 1, wherein said apertures formed on said tubular member have a width of approximately 0.120 inches.

3. The muffler as set forth in claim 1, wherein said apertures allowing fluid communication between said sound absorbing chamber and said resonating chamber have a width of approximately 0.250 inches.

4. The muffler as set forth in claim 1, wherein said apertures formed on said tubular member are arranged to provide an open area of approximately 40% to 70%.

5. The muffler as set forth in claim 1, wherein said apertures allowing fluid communication between said sound absorbing chamber and said resonating chamber are arranged to provide an open area of approximately 30% to 40%.

6. The muffler as set forth in claim 1, wherein said apertures are formed as louvers.

7. The muffler as set forth in claim 1, further comprising an outer shell surrounding said resonating chamber, wherein a centroid defined by said tubular member is located at a centroid defined by said outer shell.

8. The muffler as set forth in claim 1, wherein said muffler has a cylindrical cross-section.

9. The muffler as set forth in claim 1, further comprising a screen in surrounding contact with said tubular member.

10. (Thrice Amended) An acoustic muffler for attenuating sound waves, comprising:

an elongated straight through tubular member;

first and second inner end plates mounted about said tubular member and being spaced apart;

first and second outer end plates mounted about said tubular member and being disposed outside of said inner end plates, said tubular member extending continuously from said first outer end plate to said second outer end plate;

an inner shell coupled with said inner end plates and extending therebetween so as to define, in conjunction with said tubular member and said inner end plates, an annular sound absorbing chamber;

sound absorbing material being contained in said sound absorbing chamber;

an outer shell coupled with said inner end plates and extending therebetween so as to define, in conjunction with said inner shell and said inner end plates, an annular resonating chamber in surrounding relationship with said sound absorbing chamber;

a first and second annular end chamber defined by said tubular member, said inner and outer end plates and said outer shell, said end chambers being imperforate;

a plurality of apertures formed on said tubular member; and

a plurality of apertures formed on said inner shell.

11. The muffler as set forth in claim 10, wherein said apertures formed on said tubular member have a width of approximately 0.120 inches.

12. The muffler as set forth in claim 10, wherein said apertures formed on said inner shell have a width of approximately 0.250 inches.

13. The muffler as set forth in claim 10, wherein said apertures formed on said tubular member are arranged to provide an open area of approximately 40% to 70%.

14. The muffler as set forth in claim 10, wherein said apertures formed on said inner shell are arranged to provide an open area of approximately 30% to 40%.

15. The muffler as set forth in claim 10, wherein said apertures are formed as louvers.

16. The muffler as set forth in claim 10, wherein a centroid defined by said tubular member is located at a centroid defined by said outer shell.

17. The muffler as set forth in claim 10, wherein said muffler has a cylindrical cross-section.

18. The muffler as set forth in claim 10, further comprising a screen in surrounding contact with said tubular member.